Enable readability-container-size-empty tests

This one is a little trivial, but it does help in readability.

Signed-off-by: Ed Tanous <edtanous@google.com>
Change-Id: I5366d4eec8af2f781b3bad804131ae2eb806e3aa
diff --git a/include/webassets.hpp b/include/webassets.hpp
index f92214f..8f41f2f 100644
--- a/include/webassets.hpp
+++ b/include/webassets.hpp
@@ -102,8 +102,7 @@
             if (boost::starts_with(webpath.filename().string(), "index."))
             {
                 webpath = webpath.parent_path();
-                if (webpath.string().size() == 0 ||
-                    webpath.string().back() != '/')
+                if (webpath.string().empty() || webpath.string().back() != '/')
                 {
                     // insert the non-directory version of this path
                     webroutes::routes.insert(webpath);